“My mother studies economics, and she told me renminbi is definitely going to depreciate,” said Zuo Rui, a student at the University of North Carolina at Chapel Hill, whose family bought a total of $75,000 before the spring semester this year, three times the amount of dollars the family usually buys per semester.

As China’s economy sputters, ordinary Chinese like Zuo Rui rush to change their yuan into dollars. The People’s Bank of China has used its foreign reserves to keep the currency exchange rate at a relatively stable level. In June, China had $3.21 trillion in currency reserves, down from nearly $4 trillion in 2014. Facing pressures from capital outflows, China has tightened its oversight of the flood of money leaving the country, including increased monitoring of individuals purchasing foreign assets and greater scrutiny of foreign-currency transactions.

Despite the crackdown on underground currency markets and heightened enforcement of the $50,000 annual cap that each individual in China is allowed to buy, students have found various ways to circumvent the restrictions.

A math student at a private university in the Midwest, who asked to be unnamed due to the sensitive nature of the matter, said his father bought a total of $150,000 from last October to this January. His father, an employee of a big Chinese bank, borrowed identification cards from his coworkers to circumvent the $50,000 annual exchange ceiling, the student said.

“He works for the bank’s risk department and learns a lot about companies’ bad loans, so he is pessimistic about the current situation.”

As growing concerns about bad loans weigh on China’s economic outlook, the central bank faces the difficult task of reversing people’s expectation of the yuan’s depreciation. Although the official data shows the nonperforming loan ratio stood at 1.6%, some analysts estimate that it could be as high as 19% of total loans.

Han Zhongtian, an undergraduate student at Brown University, said his family swapped renminbi for dollars through a family friend who owns assets in the U.S. Mr. Han’s family bought dollars two times from the friend last year, and $200,000 in total. The family friend sent the dollars to a bank account in Hong Kong, where no limit of dollars bought or sold is applied. Mr. Han said the money will be used to finance his education over the next few years.